Gums (also known as hydrocolloids) are well known thickening agents, gelling agents and binding agents and have also been used as emulsifiers, foaming or whipping agents, encapsulating agents, film forming agents, flocculating or clarifying agents and crystallization inhibitors. See Carbohydrates in Food, ed. Ann-Chariotte Eliasson, pg. 285 (1996); see also Food Chemistry, ed. Owen Fennema, pg. 186-190 (1996).
Given their widespread utility, the gums are often consumed in vast quantities in industry. A problem associated with the use of gums is how to quickly ascertain a bad lot or batch of gum material provided by a bulk manufacturer of gums. Far too often, the unsuitability of the gum material is not detected until after the final product has been produced.
Complicating this problem is that feedstock for gums from natural origin are often the source of attribution to account for different viscosity patterns for gums received from different suppliers. Moreover, in order to obtain specific viscosity properties for their gums, suppliers often rely on proprietary mixing techniques to form their products.
Given the stringent regulatory laws and rules governing pharmaceutical and food compositions, it would be beneficial to detect any potential problems with a gum purchased from a supplier as early in the process of making a product as possible.
The comparison of viscosities are especially critical when using different suppliers or changing suppliers of the thickener or emulsion stabilizer compounds.
A common method of testing a gum sample is the use of gel permeation chromatography (GPC) with or without a size exclusion chromatography (SEC) system. A test sample is injected into the chromatographic system and the properties of the gum are determined via a detector system comprised of one or more of a refractive index detector and a viscometer.
The viscometric data generated can form a Mark-Houwink plot, the curvature of which can provide information about properties of the tested gum material,
However, the GPC/SEC system, in addition to being time consuming, suffers from needing expensive and sensitive equipment more suited for the small scale, controlled environment of a university laboratory rather the rigorous conditions of a factory floor.
Other methods for determining viscosity and the homogeneity of a gum include a theological method (creep and recovery test) and the use of NIR (near infrared) spectroscopy.
The creep and recovery test, a sample reacts to constant shear stress for a certain period of time by deforming (“creep”). The sample is then relieved of the shear stress so that it can recover. See ASTM-D2990 (creep test); ASTM-D2991 (stress relaxation test)
However, this method also suffers from the problems of requiring high-cost test equipment (rheometer) and being a lengthy test process when measuring the time from sample preparation to final analysis of the tested sample.
The use of NIR spectroscopy also requires high-cost test equipment and its accuracy in determining viscosity, and therefore, the homogeneity of the gum, is uncertain.
Water has also been used with gums for the purposes of viscosity assessment by forming a slurry, dispersion or solution of the gum in water. However, this form of the gum often leads to incomplete dispersion or solubilization of the gum in water and to the formation of lumps which skews the viscosity measurements.
In addition, formation of such slurries, dispersion or solutions in water may require 24-48 hours for the gum to swell and impart its optimum viscosity.
Therefore, a need still exists in the art to quickly and accurately determine the viability of using a gum.